Safety Edges on a Sliding Gate
A sliding leaf moves parallel to a fence line and creates a closing gap that narrows to nothing, which is a hazard a swing gate simply does not have. The edge placement guidance at Mount Pleasant Sliding Gates Narcoculture treats it as its own subject, because sliding gates in Mount Pleasant present entrapment points at both ends of travel and most installations protect only one.
The Two Entrapment Zones
Closing entrapment happens between the leading edge and the receiving post. Opening entrapment happens at the trailing edge as the gate travels into its parked run, and it is the one that gets forgotten, because the gate is moving away from the driveway and appears harmless. Both need sensing.
What a Safety Edge Is
A safety edge is a compressible rubber strip carrying a switching element along its length. Any contact anywhere along it signals the operator to stop and reverse. It is a contact device, which is what makes it different from a photo eye, and it is why the two are used together rather than as alternatives.
Where They Mount
An edge belongs on the leading edge of the leaf and on the trailing edge, and often on the fixed post face opposite each. A wireless edge avoids running a cable along a moving gate, at the cost of a battery that needs checking. A wired edge on a slider needs a properly rated coiled or festooned cable, because a fixed cable on a moving leaf will fatigue and fail.
Photo Eyes Cover a Different Risk
A photo eye stops the gate before contact, but its beam only covers the line it is aimed along. On a slider the useful beams are across the opening and along the parked run. The edge catches whatever the beams do not, and neither device on its own covers both zones.
Testing Both
Press each edge by hand during a cycle and confirm the reverse. Break each beam with an object and confirm the same. Do this at every service, since an edge that has been crushed by a vehicle or a beam that has drifted out of alignment gives no indication at all during ordinary operation.